Geometrical measuring and drafting



Feb. 1, 1949. c pso 2,460,713

GEOMETRICAL MEASURING AND DRAFTING INSTRUMENT Filed Feb. 10, 1948 2 Sheets-Sheet 1 f v I Fwm 1 flkosolv l8 .1 BY

17 T TORNE y Feb. 1, 1949. E. RICHARDSON 2,460,713

GEOMETRICAL MEASURING AND DRAFTING INSTRUMENT Filed Feb. 10, 1948 g Sheets-Sheet 2 I g wam r 1 INVENTOR. EWELL R ICHHRDSON ATTORNE) Patented Feb. 1, 1949 UNITED STATES PATENT OFFICE GEOMETRICAL MEASURING AND DRAFTIN G INSTRUMENT Ewell Richardson, Los Angeles, Calif. Application February 10, 1948, Serial No. 7,398

4 Claims. 1

This invention relates to a device for the solution of angles and triangles. ployed for the measuring of angles between intersecting lines and triangles and for the general drafting operations in which angles and triangles are to be constructed or solved.

It is an object of my invention to devise an instrument capable of being employed for drafting involving the construction of angles and triangles and which may be used for the measurement of the same and for the solving of trigonometric problems involving angles and triangles.

Such instruments are of general applicability and find particular utility in the solution of navigation problems.

These and other objects of my invention will be clear from the further description thereof taken together with the drawings, in which Fig. 1 is a plan view of my instrument with parts broken away for clarity;

' Fig. 2 is a section taken along line 2--2 of Fig. 1;

Fig, 3 is a fragmentary detail of two arms employed in my structure showing their relation;

Fig. 4 is a section taken along the line 4-4 of Fig. 1;

Fig. 5 is a fragmentary detail showing the re lationship of the slide and one of the arms of my device; i

Fig. 6 is a similar detail relating to another arm of my device;

Fig. 7 is a plan view of one of the arms of my device showing the slide in position;

Fig. 8 is a side view of Fig. 7;

Fig. 9 is a plan view of another arm employed in my structure showing the slide positioned therein;

Fig. 10 is a side view of Fig. 9;

Fig. 11 is a plan view of the third arm of my device showing two slides in position;

Fig. 12 is a section taken along the line lZ-IZ of Fig. 11; and

Fig. 13 is a perspective view of one of the semicircular discs employed in my structure.

My device is composed of a plurality of intersecting arms arranged in adjustable angular relationship as illustrated in the drawings.

The arms l and 8 are arranged in angularlv adjustable relation to each other and held in such relationship by means of a plate I5. Arm 8 is composed of a flat bar having a straight edge 2 suitably engraved with rule markings and carries a slot 9 which may be faced with a hard It may also be emwear-resistant surface material such as a metal strip. The arm is chamfered at l2 and [3 to give an arcuate shoulder of radius to be further described and an extension II which terminates in an upstanding arcuate flange M of radius curvature to be further explained. The upstanding flange 14 maybe of metal or other wear-resistant material. Arm l is formed similarly to that of arm 8.1m that it carries a straight edge 2 carrying ruler markings and having a slot 3 similar to the slot 9 and chamfered at 6 to give an arcuate shoulder of radius curvature equal to that of l2 and I3. It carries an extension 5 on which is positioned an upstanding flange 1 of arcuate fashion. The flange 1 may be of wearresi-stant material such as metal. which is formed with suitable protractor markings with zero centered at I! carries two concentric slots l8 and i9 centered at H and overlapped as shown in the drawings. The plate l5 may have an insert l6 which is surfaced with a wearresistant material such as a metallic surface on the underneath side of the plate l5 where the arms rub over the surface, as will be explained hereinafter. The arm 8 is mounted so that the flange M enters slot l9. The radius of curvature of the arcuate flange I is equal to the radius of curvature of the slot I8 and also centered at point H. In like manner the arcuate flange l4 enters the arcuate slot l9 being of equal radius of curvature and likewis centered at [1. As shown the arm 8 overlies arm land the plate l5 overlies arm- 8.

It Will be observed that the radiusof curvature of chamfers l2, l3, and 6 is equal to the radius of curvature of the outside edge of the semicircularplate I5. The chamfers thus form the extensions with an upper surface below the top surface of the main portion of the arms. It will also be observed that due to the formation as indicated the underneath surface of arm l and the underneath surface of arm 8 to the right of the chamfers l2 and I3, and also 6, as viewed on Fig. 7, are coplanar so that the two arms may be laid upon a surface in such fashion that the inside edges 2 and 2' form ruling surfaces.

It will also be observed, as will be more fully explained below, that the arms l and 8 may be angularly adjusted with relation to each other by sliding the flanges 1 and it inside the slots is and f9 and at all times the edges 2 and? will intersect the edge of the plate 15 at point ll, i; e., at 0 of the protractor scale. The action of these two arms may therefore be described as a The plate l5 fore possible to see the underneath edges 2 and 2", particularly if the arms are alsomade of a transparent material such as methylmethacrylate plastic, Celluloid or glass, and in that way the angle between edges 2 and 2 may be read from the protractor plate I5. The instrument thus in this stage, that is, composed merely of l ed by the angular adjustment permitted by the cooperationpf the slides and the plates 30 and 35. It will also be observed that for any angular setting of the arm 20 with respect to either arm I or 8, the ruled edges will intersect at 38' and arms I and 8 and the plate I5, is useful for construction or measurement of an angleby settingthe point I! over the vertex of the angle,

It will also be observed that because of the presence of the chamfers the arms may be opened 180 from each other, the circular edge of the plate I5 passing over the extensions 5 and II and by the chamfersfi and I2, since the radius of curvature of I2 and 6 is equal to the radius of curvature, of the edge .of plate I5 and equally centered at I I. s

Inor'der to co'mpletethe mechanism for the forming of a triangle, Ihave also provided an additional arm and two additional plates 38 and' 35 to be next described.

Slidably positioned within the slot 9 is a block 28 of thickness equal to the maximum thickness of arm 8 and carrying an upstanding arcuate flange 2'1 directed in the same direction as the flange I4. S lid 'a bly positioned in slot 3 of arm I be like slide 28 of thickness equal to the maximum thickness of arm I and carrying an upstanding arcuate flange29 directed in the same direction as flange 1. The arm 20 has a ruled edge 2" and a slot 2| faced with a hard wearresistant facing such as that shown for arms I and 8 and carries slidably mounted therein two slides 2 2 and 2.4, respectively of width equal to the; thickness ofarm 20 and carrying depending arcuate-flange 23 and 25 respectively.

In mounting jthearm 20 upon arms 8 and I plates tp and-35 are provided of construction quitesi'milarto that of plate l5. The plate, carries a zero mark 84', being the center of the semi-circular disc, and carries a wear resistant plate- 3'I in which are positioned two arcuate grooves 32 and 32' centered at 34. The radius of curvature of grooves 32 and 32" is the same as the radius of curvature ofrthe flanges29 and 23 and similarly centered at 34 so that the plate 30 may be placed on top of arm I, the flange 29 entering the groove 32', In like manner the plate 35 is constructed like3'0 and carries two arcuate slots 37 and 38 centered at 38' which is the center of the 'semi-circula'r'edge of plate 35. The upstanding flange 21 will enter the slot 38, being of equal and like curvature, and the depending flange 25 of slide 22 will enter the slot 31, being of equal and like curvature. In this fashion the plate 30 may be placed upon arm I and the plate 35 may be placed upon arm *8 and the arm 20 may overlie-theplates' 30' and '35 in such fashion that the dependingflanges. 25 and 23 enter the corresponding arcs of the respective plates Hand 30, while the upstanding flanges 21 and 29 of the corresponding arms I and 8 enter upwardly into the slots 38 and 325..

It will thus be seen that the arm 20 can be madeto take any angular position with respect to the arms I and8 such that the sum of the angles 3d respectivelyan'd in this fashion the angle between arm 20 and corresponding arms I and 8 maybe read; respectively upon the plates 30 and 35;

While I have described a particular embodimentof my invention for the purpose of ilustration, it should be understood that various modiflcationsand adaptations thereof may be made within the spirit of my invention as set forth in e p cl imsj 1. A geometricalinstrum'ent comprising a plate, a pair of concentric arcuate slots in said plate, an arm, an arcuate flange on said arm, of curvature similar to the curvature of one of said slots and s'lidably,position'ed in said slot, a second arm, a second arcuateflan'ge on saidsecond arm, of curvature similar to the other of said slots and slidably positioned in said other slot.

2; A geometrical instrument comprising a protractor plate, a protractonscale on said plate, a zero mark on saidprotractor;scale, a pair of concentric arcuate slots in said plate, an arm, an arcuate flange on said arm, of curvature similar to the "curvature of oneoi said slots and slidably positionedin-said slot, at second arm, a second arcuate flange on said second arm, of curvature similar to the other of said slots and slidably positioned in said other-slot, each of said arms havinga ruled straight edge along opposed longitudinal faces of said arms, said edges intersecting-at said ze'ro mark.

'3. A g'eometricalins'trument Comprising a protractor plate, a protract'or-scale on said plate, a

zero mark on said protractor scale, a pair of concentric arcuate 510mm said plate, an arm, an arcuate flangebnsaid arm, of curvature similar to the curvature of one of said slots and slidably positioned in said slot-,a second arm, a second arcuate flange on said second arm, of curvature similar to the other of saidslots and *slidably positioned in said other 'slot, 'each--ofsaid arms having a ruled straight edge along opp'o'sed-lohgitudinal face's of saida'rm's, saidedge's intersecting at said zero mark, said plate also having a circularedge, centered at said zero mark, each of said arms being chamfered to for'm an'arcuate chamfer of .straightedgegalong opposed longitudinal faces between the arms 2 0 and, I and, between 8 and zuaiia between-aand I equals ofsaid arms,- saidi-ed es intersecting at said zero mark, said plate also having a circular edge centered at said zero mark, each of said arms being chamfered to form an arcuate chamfer of radius of curvature substantially equal to the curvature of said circular edge and centered at said zero mark on said plate, each of said arms containing a slot, a slidable block in said slot, an arcuate ridge on each of said blocks, a third arm, a slot in said third arm, a pair of blocks slidably placed in the slot in said third arm, each of said pair of blocks having an arcuate ridge, a pair of plates, each of said plates carrying a pair of concentric slots, said plates each being placed between the third arm and said first mentioned arm, the arcuate flanges of said blocks entering said arcuate slots and being slidably positioned therein.

EWELL RICHARDSON.

No references cited. 

